Java Regex to Flutter Regex

Question

I am trying to convert a Java regex to a Flutter(Dart) regex but I am having trouble.

My Java Code and Regex example, witch returns Matching:

    public static void main(String[] args) {
    String EMAIL_VALIDATION_REGEX = "^[a-zA-Z0-9_+&*-]+(?:\\.[a-zA-Z0-9_+&*-]+)*@(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,7}$";
    String email = "[email protected]";
    if(!Pattern.matches(EMAIL_VALIDATION_REGEX, email)) {
        System.out.println("Not matching!");
    }else {
        System.out.println("Matching!");
    }
}

My Flutter Code example witch returns Not Matching:

    final RegExp _emailRegex = RegExp(
    r"^[a-zA-Z0-9_+&*-]+(?:\\.[a-zA-Z0-9_+&*-]+)*@(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,7}$",
    caseSensitive: false,
    multiLine: false);

final String _email = "[email protected]";

if (!_emailRegex.hasMatch(_email)) {
  print("Not Matching!");
} else {
  print("Matching!");
}

I have basically copied the regex that i use in java and added r as a prefix. Can someone help me identify the issue with this code?

Thomas Timbul · Accepted Answer · 2022-02-03 12:50:53Z

The r prefix creates a raw String. As a result you don't need to double escape your \\. sequence. Use a single backslash: \.

See https://api.flutter.dev/flutter/dart-core/RegExp-class.html

Note the use of a raw string (a string prefixed with r) in the example above. Use a raw string to treat each character in a string as a literal character.

And https://www.learndartprogramming.com/fundamentals/strings-and-raw-strings-in-dart/

What is a raw strings in Dart: In Dart programming language, raw strings are a type of strings where special characters such as \ do not get special treatment.

Raw strings are useful when you want to define a String that has a lot of special characters.

Raw strings are also useful when you are defining complex regular expressions that otherwise are difficlut to define using the single and double quotes.

The main advantage of using a raw String with regular expressions is that, unlike in Java, you can copy and paste your regex and test it easily in other tools, such as https://www.regexr.com, without worrying about additional escaping.

Collectives™ on Stack Overflow

Java Regex to Flutter Regex

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related